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Effects of acute isometric resistance exercise on cervicomedullary motor evoked potentials
Author(s) -
Nuzzo J. L.,
Barry B. K.,
Gandevia S. C.,
Taylor J. L.
Publication year - 2018
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/sms.13053
Subject(s) - isometric exercise , biceps , medicine , forearm , physical medicine and rehabilitation , elbow flexion , physical therapy , elbow , anatomy
Cervicomedullary motor evoked potentials ( CMEP s) in relaxed biceps brachii have been reported to facilitate after acute isometric exercise of the elbow flexors. This facilitation, which reflects either enhanced corticospinal transmission or increased motoneurone excitability, has only been documented in the limb posture used during exercise. In Experiment 1, we tested if these spinal changes “transfer” to a second posture. Fourteen individuals completed 12 sets of high‐force isometric contractions of the elbow flexors with the forearm pronated. Before and after exercise, biceps CMEP s were acquired with the forearm either pronated or supinated. CMEP s in pronation and supination were facilitated after exercise, indicating transfer (57.5 ± 55.5% and 53.9 ± 54.9%, respectively; mean ± SD ). In Experiment 2, we examined if exercise posture influences the effect that exercise has on CMEP s. A different sample of 14 individuals performed isometric exercise in 2 sessions. In one, exercise was performed in supination. In the other, exercise was performed in pronation. Exercise intensity and volume were the same as in Experiment 1, as were participant characteristics. CMEP s were unchanged after exercise in supination (13.6 ± 31.2%) and pronation (7.7 ± 41.5%). The absence of an effect differs from the finding of Experiment 1. Thus, effects of acute isometric resistance exercise on corticospinal transmission and/or motoneurone excitability are not as consistent as previously thought. When exercise induces this spinal change, the effect is not specific to the posture used for exercise. However, the change does not always occur, and the reasons for this remain unknown.